High-vacuum device for influencing currents



- Dec. 15, 19 25.

J. E. LILIENFELD HIGH VACUUM DEVICE FOR INFLUENCING CURRENTS Filed Sept; 5, 1921 Patented Dec. 15, 1925.

' UNITED STATES iumus E. LILIENFELD, or xnw GARDENS, NEW YORK.

HIGH-VACUUM DEVICE FOR INFLUENCING CURRENT S.

Applicati on filedieptember 3, 1921. I Serial No. 498,391.

.tubes and more particularly to devices of this character for influencing electric currents.

It is the object of the invention to produce a simple and eflicient device of the type used for setting up oscillations and it is a particular object to provide simple and highly eflicient high vacuum devices for use as transmitters and amphfiers 1n radlo work.

The principle of operation 1s based upon the discovery that an intense'discharge can be started in an extremely high vacuum between cold electrodes if the cathode is provided with surfaces of small curvature and if these surface .or surfaces are sufliciently close to an anodic surface. Provided that the electrodes are made of a highly refractory material, that they have been freed of the occluded gases by heating, preferably by means of an electronic bombardment, and. that further the vacuum is sufficiently high, no ionization and no discharge between the electrodes will take place. Consequently no deterioration of the cathodically active surface occurs and the operation of the tube is uniform and constant. Incidents such as the burning throughof the wires of the hot cathode tubes are eliminated and because of the absence of a heating circuit a'materi'al simplification of the apparatus is obtained.

The voltage required is a function-of the geometrical arrangement of the electrodes. It increases in proportion to the distance be tween the electrodes and the radius of curvature of the cathodic active surface or" surfaces as the case may be. In order'to make it possible to operate with a relatively low voltage the electrodes must be placed .very close together and the cathode must be provided with a large number of very thin and very sharp points.

In order to utilize the discharge for the particular purpose referred to, the tube must contain in addition to the cathodic active surface and the anodic surface placed close to the former one or more other electrodes.

Some of these additional electrodes may' be provided in order to receive the flow of electrons originated by the discharge between the anode and the cathode, while other additional electrodes may be loadedto different potentials and thereby be employed to change either the discharge between the anode and the cathode or the flow of electrons to other electrodes.

For a full understanding of the invention reference is had to the accompanying drawings in which- Fig. l is a diagrammatic representation of one form embodying the invention;

Fig. 2shows a modification thereof;

Fig. 3 is a diagrammatic representation of a different arrangement for carrying out the invention;

Fig. 4 is a diagrammatic view showing a modification ofthe form shown in Fig. 8;

Figs. 5 and 6 are fragmentary sectional views of detail involving a modification of the forms of electrodes indicated in Figs. 1 and 2.

Fig. 7 is a fragmentary sectional view of detail involving a modification of the forms of electrodes indicated in Fig. '3 and Fig. 8 is a diagrammatic view of an arrangement ofelectrodes involving another modification of Fig. 1.

All forms disclosed include, aside from the usual electrodes, an auxiliary anode in correlation therewith, a simple arrangement being shown in Figs..3 and 4.

In Fig. 3, Kindicates the cathode and A and A are the anodes. D'represents a dynamo having one pole connected to the cathode and energizing the anodes through branch circuits including the inductances L and L the capacities C and C and the auxiliary inductance L By means of a switch S the branch circuit L C L and anode A may be disconnected from the dynamo and the branch circuit leading to the anode A While the switch S is open, simply a nonoscillatory discharge will pass between K and A When the switch is closed, the anode A comes into play and oscillations are started by the inductive interaction of coil L on coil L in the circuits C, Li and 0,, L The circuits containing L and L must be tuned to a corresponding frequency, while lln those containing L and L may be in such condition of tuning and phase that the oscillations generated in both may be superposed at a certain antenna,

In Fig. 4 one pole of the dynamo D, is connected to the cathode K, through the inductance L and to the anode A, through a resistance R, and an inductance L The other pole of the dynamo is connected to the anode A, through a resistance R an inductance L and a switch P. The anodes A, and A, are interconnected through a resistance R a condenser C and an inductance L in series relation. The branch lP C L is the oscillatory circuit proper, as is obvious.

In the arrangement shown in Figs. 3 and 4 the electrons flow directly to the anodes. However, there are other ways of utilizing the electronic discharge for the purposes of the invention, as for instance illustrated in Figs. 1 and 2.

The arrangement shown in Figs. 1 and 2 isbased on two observations: (1) That at the points of impact of the electrons on the anode a new flowof electrons-reflected and secondary-is started, (2) That the electrons coming from the active cathodic surfaces are accelerated in such close proximity to these surfaces that thereafter they are not necessarily driven by the field to the nearest part of the anode, but may as likely travel longer paths to more distant anodic surfaces.

The cathodically active surfaces of the electrode K are placed close to the anodic electrode H while A is the anode which receives the combined flow of primary and secondary electrons of the system K H.

One pole of the dynamo D is connected to the cathode while from the other pole through the oscillating circuit including the capacity and inductance L, a charge is impressed on the anode A Coil L is inductively'coupled with L and therefore an oscillating potential is impressed upon the anode H producing an oscillatory flow of electrons in the tube, provided that the circuits containing coil L and coil L respectively, are tuned to a corresponding fre quency.

Another way of energizing the device shown. in Fig. 1 can be based on the fact that while K H is energized and A kept on different negative voltages, the higher the negative volt-age of A the less the current flowing to this electrode. This negative characteristic of the discharge flowing to A may be used for the production of oscillations in a circuit similar to the Poulson are.

By similar means well known in the art an amplifying circuit can be set into operation.

The device illustrated in Fig. 2 difi'ers from that of Fig. 1 principally only by the menace interposition of a grid G between the auxiliary anode H and the anode A This grid acts upon the electronic stream originated in the system K H according to its potential and permits a larger or smaller part of the stream to strike on A so that in this way oscillations will be produced.

In this case the oscillating potential produced by the inductive action of coil L upon coil L is imparted to the grid G and therefrom the oscillations of the discharge in the tube are originated, provided that the circuits of L and L are tuned as indicated above.

The dynamo D is connected to the cathode K, and the auxiliary anode H and causes the release of electrons from the system K H while the dynamo D is instrumental in relaying the electrons thus liberated t0 the anode A L 6 represent the oscillatory circuit and L the inductance which impresses upon the grid G the voltage which governs the electronic stream to A While I have shown two separate dynamos, it is of course possible, as is well understood, to use a single dynamo having its poles interconnected by a resistor for establishing any desired point of potential between the potentials of the opposite poles.

In order to increase the active cathodic surface and make the devices symmetrical and easier to operate the constructions so far described may be modified in various ways.

Instead of the arrangement shown in Fig. 1 a tube may be constructed with concentric electrodes. Thus, as shown in Fig. 5 the cathode K may be surrounded by the auxiliary anode H and this system in turn may be surrounded by the anode A Similarly, as shown in Fig. 6, the concentric arrangement including the cathode K the auxiliary anode H the grid G and the anode A, may replace the arrangement shown in Fig. 2.

Again the form and disposition of the electrodes according to Figs. 3 and 4 may be modified according to the disclosure in Fig. 7. The cathode K has the form of a disk and is surrounded by two rings A and A constituting the anodes.

As indicated in Fig. 8 which representsan arrangement such as shown in Figs. 1 and 5, the cathode may comprise a plurality of disks K in parallel relation and the auxiliary anode may similarly comprise a plurality of annular disks H preferably in alignment with the disks K and concentrically disposed thereto, while the anode may be a cylindrical tube A concentrically disposed about the anode elements.

There are, of course, other changes and modifications of which the electrodes and their mutual relationship are susceptible. Thus while I have indicated in Figs. 5, 6 and 7 the cathodes as innermost in the arrangement, the relative positions of the electrodes may be readily reversed.

For the purpose of reducing the voltagetrodes distances it is advisable to dispose the stems supporting the electrodes in planes substantially at right angle to the direction of the gap or the discharge so that the expansion due to changes of temperature may be practically without effect on the size of the gap.

In the foregoing I have referred only to arrangements in'which single electrodes were used. Within the scope ofthe invention it is of course possible to use multiple electrodes. Thus for the sake of example the arrangement generally represented by Fig. 1 and modified according to Fig. 4 may include a plurality of superposed disks K,, a like plurality of rings H and a tube section A constituting the cathode, the auxiliary anode and the anode respectively.

To obtain a suflicient vacuum, not only the anode, but also the cathodes must be bombarded during the evacuation by an electronic stream.

For this purpose either special cathodes with active surfaces may be provided or such surfaces may be mounted on the anode so that upon inverting the current electrons are released in the direction of the cathode which electrons bombard the latter thereby heating it up and expelling all occluded gases.

Arrangements for this purpose are described in my application Serial No. 498,392 filed Sept. 3, 1921.

I claim 1. Apparatus of the characterdescribed, comprising an envelope evacuated to such a degree that ionization is, substantially prevented, electrodes including an unheated cathode having an active surface or surfaces of small radius of curvature in' close prox-,

imity to an anode for producing an electronic discharge and means for producing a separate field of force to modify the character of the discharge.

2. Apparatus of the character described, comprising an envelope evacuated to such a degree that ionization is substantially pretvented, an unheated cathode having active surfaces of small radius of curvature, a

plurality of anodes in close proximity to said surfaces for producing an electronicdischarge and means for influencing at will the discharge to selectively pass to one or the other of said anodes.

3. Apparatus of the character described, comprising anenvelope evacuated to such a degree that ionization is substantially prevented, an unheated cathode having a surface of small curvature, an anode in close proximity to said surface, a second anode, means for discharging a stream of electrons from the cathode and means including the second anode for modifying said stream.

4. Apparatus of the character described, comprising an envelope evacuated to such a degree that ionization is substantially prevented, an unheated cathode having a surface of small radius of curvature, an anode in close proximity to the said surface, a

second anode, means including the cathode and the first anode for producing a non-oscillatory discharge and means including the second anode for producing an oscillatory discharge. I

5. Apparatus of the character described,

comprising an envelope evacuated to such a degree that ionization is substantially prevented, an unheated cathode having a surface of small radius of curvature, an anode in close proximity to the said surface, means for releasing'a stream of electrons from the cathode, another anode andmeans for di recting the primary electrons emitted from the cathode together with the secondary electrons rieleased due to the impact of the primary electrons upon the first anode, to the additional anode.

6. Apparatus according to claim 5 including means including a'grid between the first anode and the additional anode.

8. Apparatus of the character described,

'eomprising an envelope evacuated to such a degree that ionization is substantially prevented, an unheated cathode having a surface of small radius of curvature, an anode in close proximity to said surface, means for releasing a stream of electrons from the cathode, a plurality of additional anodes and means for acting upon the additional anodes to direct the primary electrons emitted fromthe cathode together with the secondary electrons released from the first anode upon the additional anodes.

9. Apparatus according to claim 8 in which one o3 the additional anodes has the shape of a gri 10. Apparatus of the character described,

comprising an envelope evacuated to such a degree that ionization is substantially prevented, an unheated cathode, a plurality of anodes disposed in substantially the same direction at different distances from the cathode and means for differently acting upon the cathode and the anodes to impress different charges upon the latter.

11. In a high vacuum device, the combination of a tube evacuated to such a degree 10 that ionization is substantially prevented and electrodes therein including an unheated cathodehaving a relatively large number of sharp vpoints extending into close proximity to an anodic surface. In testimony whereof, I afiix my signature.

JULIUS E. LILIENFELD. 

